refactor(cli): move /system upgrade hint into thinking tips (#1411)

Co-authored-by: Letta Code <noreply@letta.com>

src/tests/cli/thinkingMessages.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test";
 import {
   getRandomThinkingMessage,
   getRandomThinkingTip,
+  SYSTEM_PROMPT_UPGRADE_TIP,
   THINKING_TIPS,
 } from "../../cli/helpers/thinkingMessages";
 
@@ -54,4 +55,12 @@ describe("Thinking messages", () => {
     expect(tip.length).toBeGreaterThan(0);
     expect((THINKING_TIPS as readonly string[]).includes(tip)).toBe(true);
   });
+
+  test("can exclude /system upgrade tip from the selection pool", () => {
+    const tips = Array.from({ length: 50 }, () =>
+      getRandomThinkingTip({ includeSystemPromptUpgradeTip: false }),
+    );
+
+    expect(tips.every((tip) => tip !== SYSTEM_PROMPT_UPGRADE_TIP)).toBe(true);
+  });
 });